Under or over proofed? Dough also keeps flattening once turned out. SoS!

• 500g 13.5% Bread flour
• 380g water
• 110g starter
• 78% hydration
• 2% salt

1 hour autolyse. Mix in salt and starter with stand mixer until dough started to pick up off sides. 4 stretch and folds. 1 lamination. 2 coil folds. All approx 20-30 mins apart.

This fermented for around 5-6 hours at 27-29°C until my (much smaller) sample had increased in volume by just under 50% and there was visible activity on top of my main dough.

I preshaped very gently then shaped with this method, very similar ito. tension to the video . Benefit of hindsight, i would have expected a bit more air in the dough at this stage but i am still getting used to higher hydration

I rested at room temp for around 1 hour 30 until the dough was recovering from pokes pretty slowly before fridging for 12 hours and baking.

My big qualm with any dough I've tried over about 75% hydration is they just die on me the second they come out of the banneton. I feel in this case like maybe i under fermented and/or then didn't let it proof up enough in the banneton.

I have also seen people say that if your dough volume is too small for the banneton then this can happen, but i can't imagine why.

Generally my dough just feels super fragile when shaping and then when removing from banneton, despite seemingly developing great strength during fermentation (easy window panes, etc)

You can kind of see in the pic where the loaf has sagged back down when trying to rise because it spread so badly. Crumb looks surprisingly decent though…